Let me know how it works, but I don't think you'll have to worry to much about the foam although the zip ties are the weak point here. I think if it does flip at speed and slides enough the ties will pop off then it will be skidding on the head again. I think the PVC idea is something to look into, maybe cutting a piece of pipe that can slide over and leave a ring on the top and a ring on the bottom to ziptie to the the lower head with cutouts to allow cooling still. Its too hard to explain, I'll draw up a diagram and post it that would be easier.